Injection Molded Solder (IMS) is a process used to produce solder bumps on a semiconductor wafer surface. Referring to FIG. 1, the IMS process 30 includes depositing solder into mold cavities (34), forming a pattern on the semiconductor wafer surface (32), aligning the filled mold cavities with the patterned semiconductor wafer surface and then transferring the solder from the mold cavities to the semiconductor wafer surface (38). Solder bumps are formed in a glass mold plate 82 by injecting molten solder into the etched mold cavities. The etched cavities match the pattern of solder bumps required on the semiconductor wafer surface. The process provides fine pitch placement of the solder bumps in the range of 10 to 500 micrometers separation distance between adjacent solder bumps.
The IMS process has been tested and applied for laboratory scale applications. It is desirable to provide a scale-up process and a high volume manufacturing (HVM) apparatus designed to optimize the high volume manufacturing process. A critical aspect of the scale-up process involves the complete filling of the mold cavities. It is desirable to fill all mold cavities uniformly with solder without leaving some cavities either not filled or partially filled or overfilled.